Edible herbs are derived from a family of plants which are commonly referred to as herbs and spices and are used as flavorants in foods and food preparations.
Fresh herbs, such as parsley, oregano, garlic and the like add much desired flavor to many foods. However, they are only available on a seasonal basis and have a limited shelf-life, since they are very prone to spoilage. To overcome problems of seasonal availability and limited shelf-life, herbs are usually dehydrated and available in a dry form. Several drying methods have been employed to carry out dehydration of fresh herbs, namely, air drying, vacuum drying, and freeze drying. Unfortunately, it has been found that during such drying processes, the natural flavor of the herbs may be altered and sometimes even severely diminished. Furthermore, dehydrated herbs undergo oxidation during storage resulting in discoloration and further alteration or loss of flavor. Oxidation of dehydrated herbs during storage has been somewhat curtailed by use of undesirable chemical antioxidants which may also detract from the natural herb flavor.
U.K. Pat. No. 2,014,429B describes several prior art techniques for preserving herbs in a dry state including pasteurizing or sterilizing which, this patent indicates, results in denaturation of the taste and of the color; and preserving herbs in an acid environment, such as vinegars or other acid food products, which results in decomposition of the chlorophyll in the treated herbs and thus considerable modification of color. This U.K. patent indicates that the disadvantages associated with the afore-described prior art herb preservation techniques may be overcome by preserving herbs at ambient temperature, without heat treatment, without using chemical preservatives and without modification of acidity. This is accomplished by adding large amounts of wetting agent, such as sodium chloride, glycols, such as 1,2-propylene glycol, glycerol and sugars, such as sucrose and sorbital and optionally edible oil. The wetting agent gives the herbs a water activity of less than 0.90. The water activity represents the availability of water present in the herbs for participating in chemical and biological processes, so that the number of germs present during preserving, which may affect organoleptic quality of the herbs, is reduced as water activity is reduced. Furthermore, in Example 4, this U.K. patent shows that an unsterilized herb composition which contains 10% salt has an acceptable water activity of 0.85 so that it retains organoleptic qualities after a years' preservation at 25.degree. C., while in Example 5, an unsterilized herb preparation which contains only 5% salt has an unacceptable water activity of 0.94 and unacceptable stability in flavor and color after only 3 months' storage.
Although the herb compositions described in the U.K. patent are stable over long periods of time due to the presence of relatively large amounts of wetting agent, such as sodium chloride, glycols or glycerol, the flavor of the herb preparations is likely to be altered due to the presence of such large amounts of such wetting agents. Accordingly, these herb preparations will not be normally used as a spread.
Thus, a stable sterile herb composition which is available all year round and retains its flavor even after prolonged periods of time and which can even be used in food spreads would be a most welcomed addition to the food preparation industry.